System for regenerating fluidizable catalyst particles

ABSTRACT

A hydrocarbon conversion-catalyst regeneration operation is described which relies upon an upflowing fluid catalyst mass generally decreasing in density of catalyst particles superimposed by an upflowing more dispersed catalyst phase undergoing catalyst regeneration and combustion of combustible materials to effect elevated temperature regeneration of catalyst deactivated by hydrocarbonaceous material under conditions providing low CO levels in the flue gas and generally less than 0.15 mol percent in the flue gas separated from regenerated catalyst particles. Regenerated catalyst at an elevated temperature of regeneration is mixed with spent catalyst recovered from hydrocarbon conversion in a first contact zone in the presence of a fluidizing gas to obtain an initial mix temperature of at least 1175° F. before contact with a secondary oxygen containing regeneration gas stream in a more dense catalyst phase as a part of the upflowing fluid catalyst mass. The ratio of hot regenerated catalyst to spent catalyst is restricted to obtain a mix temperature particularly promoting the combustion of hydrocarbonaceous material with oxygen containing gas in the upflowing catalyst phases comprising dense and dispersed catalyst phase so as to recover catalyst discharge from said uppermost dispersed catalyst phase at a temperature of at least 1350°  F.

This Application is a division of copending application Ser. No. 742,806filed Nov. 18, 1976 as a is a Continuation-In-Part of Ser. No. 479,726,filed on June 17, 1974, both now abandoned.

BACKGROUND OF THE INVENTION

The field of catalytic cracking and particularly fluid catalystoperations have undergone significant development improvements dueprimarily to advances in catalyst technology and product distributionobtained therefrom. With the advent of high activity catalyst andparticularly crystalline zeolite cracking catalysts, new areas ofoperating technology have been encountered requiring even furtherrefinements in processing techniques to take advantage of the highcatalyst activity, selectivity and operating sensitivity. The presentinvention therefore is concerned with a combination operation comprisinghydrocarbon conversion and regeneration of the catalyst employedtherein. In a particular aspect the present invention is concerned withthe technique of regenerating a low coke producing crystalline zeolitehydrocarbon conversion catalyst containing deactivating deposits ofcarbonaceous material.

SUMMARY OF THE INVENTION

The present invention relates to the conversion of hydrocarbon feedmaterials in the presence of high activity fluidizable crystallinezeolite containing catalyst particles and the regeneration of thecatalyst particles to remove deactivating coke deposits by burning. In amore particular aspect the present invention is concerned with themethod and system for regenerating fluidizable catalyst particles andparticularly a crystalline zeolite containing cracking catalystinitially containing carbonaceous deposits under more efficientregenerating conditions promoting the recovery of heat available throughthe burning of combustible material including the carbonaceous depositsof a hydrocarbon conversion operation. In yet another aspect, theinvention is concerned with the method and apparatus for obtaining aparticular relationship of operating parameters coupled in a mannerpromoting a suspended catalyst phase removal of deactivating deposits ofcarbonaceous material for high activity hydrocarbon conversion catalystparticles and heating thereof to an elevated temperature.

In one aspect of the hydrocarbon conversion-catalyst regeneration systemof the present invention, a relatively dense fluid upflowing catalystmass in open communication there above with an upflowing more dispersedphase catalyst regeneration operation in apparatus resembling a bud vasein cross section is employed for effecting a relatively high temperatureregeneration of catalyst particles and combustion of formed carbonmonoxide. Regenerated catalyst recovered from the dispersed catalystphase regeneration section is collected and transferred to an adjacentriser hydrocarbon conversion operation wherein conversion of ahydrocarbon feed such as gas oil with or without either of higher andlower boiling materials such as gaseous C₅ minus hydrocarbons; loweralcohols, such as, methanol; residual oils and heavy recycle products ofcatalytic cracking as well as hydrogenated feeds is accomplished withthe hot regenerated cracking catalyst at a temperature of at least about900° F.

The catalyst employed in the operation of this invention is preferably ahigh activity crystalline zeolite catalyst of fluidizable particle sizewhich is transferred in suspended phase condition through one or moreriser conversion zones providing a hydrocarbon residence time in therange of 0.5 to about 10 seconds and more usually less than about 8seconds. High temperature riser conversions at temperatures of at least1000° F. and a hydrocarbon residence time up to 10 seconds but moreusually from 1 to 8 seconds hydrocarbon residence time is not unusualand desirable for some operations before separating vaporous hydrocarbonmaterials comprising hydrocarbon conversion products from suspendedcatalyst. Cyclonic separation of catalyst from hydrocarbons isparticularly desirable for separating and restricting the hydrocarbonresidence time with catalyst particles. During the hydrocarbonconversion step, carbonaceous deposits accumulate on the catalystparticles and the particles entrain some hydrocarbonaceous material uponremoval from the catalyst cyclonic separation step. The entrainedhydrocarbonaceous material is thereafter partially removed withstripping gas in a separate catalyst stripping zone. Hydrocarbonconversion products separated from the catalyst including strippedmaterials are usually combined and passed to a common productfractionation step. Stripped catalyst containing deposited deactivatingamounts of carbonaceous material hereinafter referred to as coke is thenpassed to the catalyst regeneration operation of the present invention.

The regeneration technique, system and apparatus of the presentinvention is unique in many respects for accomplishing an efficientremoval of carbonaceous material or coke deposits from the catalystparticles. Maximizing the recovery of heat available through the cokeremoval operation of this invention is particularly desirable. Theregeneration technique and apparatus of this invention relies uponcontrolling the formation of an initial mix of deactivated catalyst withhot regenerated catalyst to provide a predetermined mix ratio andtemperature of at least 1175° F. which is discharged from a riser mixzone into the lower portion of an upflowing relatively dense fluid massof catalyst in the lower bulb portion of the regeneration zone. Arelatively high temperature profile is maintained in the catalystregeneration apparatus combination of this invention in which theconcentration of catalyst particles in regeneration gas variesconsiderably and is generally in the range of from about 1 to 40lbs/cu.ft. but preferably it is as low as about 1.5 lbs/cu.ft. in theupper portion of the dispersed catalyst phase regeneration section. Theregeneration gas velocity in the upflowing mass of catalyst ispreferably at least 3 ft./sec. to obtain the desired upward catalystflow particularly in the more restricted upper portion of theregeneration zone of smaller diameter. The restricted regenerationsection may be tapered and of smaller diameter in the upper portion thanin the lower portion. The regeneration zone and apparatus resembles abud vase in cross section in its major portion to which the catalyst mixis introduced by a relatively short riser means.

The high temperature profile of the regeneration operation is initiallyobtained and promoted by the mixing of hot regenerated catalyst withstripped deactivated carbon containing catalyst in the lower portion ofa relatively short conduit means or riser mixing zone in proportions orratios to provide an initial catalyst mix temperature of at least 1175°F. and preferably about 1200° F. The catalyst mixture thus formed iscontacted with preheated oxygen containing regeneration gas such as airunder conditions to form a suspension and initiate combustion ofcarbonaceous deposits as the suspension passes upwardly through theriser mixer conduit. Thus, in the system of the present invention arequired amount of hot regenerated catalyst mixed with coke deactivatedcatalyst to form a mix temperature of at least 1175° F. in the riser isconveyed with oxygen containing gas and discharged generally radiallyinto the lower portion of the relatively dense fluid mass of catalystundergoing regeneration in the bottom enlarged portion of theregenerator. The riser mixer is provided in a specific arrangement witha plurality of elongated openings in the upper periphery of the riserand beneath the capped upper end thereof to effect the radial dischargeof the suspension into the more dense fluid bed phase. However, otherapparatus arrangements which will accomplish this result may also beemployed. Additional regeneration gas at an elevated temperature ispassed into the lower bottom portion of the dense catalyst mass beneaththe riser outlet of the mixing zone if desired. In the dense fluidcatalyst mass section of the catalyst regeneration operation, sufficientoxygen containing regeneration gas or air is added to the lower portionof the catalyst thereby causing it to move generally upwardly throughthe regeneration zone from the dense mass through the dispersed catalystphase section thereabove of reduced cross-sectional area. Provision isalso made for adding supplemental oxygen containing regeneration gas asrequired to one or more sections of the upwardly flowing catalyst in theregeneration zone to promote the conversion of CO to CO₂. In thisarrangement, it has been found that too high a particle density in theupflowing dispersed catalyst phase may operate to quench the conversionof CO to CO₂ desired to be accomplished before discharge from the riserregenerator into the enlarged catalyst settling zone. However,maintaining a particle density in the suspended catalyst phase belowabout 8 lbs/cu.ft. and more usually below about 5 and particularly 3lbs/cu.ft. permits combustion of CO in an upper portion of therestricted diameter riser regeneration section. Combustion of materialin the upper portion of the enlarged settling section under even lowercatalyst particle density conditions is generally not desirable orneeded in the arrangement of this invention.

The riser regeneration zone or regeneration vessel may take onsubstantially any shape, cylindrical, tapered or bud vase shaped asshown in the drawing or a combination thereof which will provide therestricted operating parameters of the invention as herein defined.

The regenerating technique and system or apparatus of this inventionrelies upon forming an initial high mix temperature of at least 1175°F., comprising hot regenerated catalyst particles and coke deactivatedcatalyst to initiate coke burning at the elevated temperature conditionsupon contact with regeneration oxygen containing gas. A dense anddispersed catalyst phase regeneration system promoting the combustion ofcarbonaceous material and conversion of formed CO to CO₂ is particularlypromoted and the recovery of heat thus generated is absorbed by catalystparticles dispersed therein. In this combination the combustiongas-catalyst particle suspension discharged from the upper end of theriser regeneration zone will normally reach a temperature of at leastabout 1350° F. and as high as 1400° F. or 1600° F. In such a system thefirst oxygen containing regeneration gas stream is introduced in thefirst riser catalyst mix zone discharging into the bottom or lowerportion of a relatively large mass of catalyst in a dense fluid bedcondition in the lower portion of the regeneration zone. Secondaryregeneration gas is introduced to a lower portion of the cross sectionalarea of the large mass of dense fluid catalyst in regeneration sectionas required to complete combustion of combustibles and transportcatalyst upwardly through the dispersed phase section of theregeneration zone. One or more downstream regeneration gas inlets arealso provided for use as required to promote a more complete combustionof CO and coke deposits. Preheating of the primary as well as thesecondary regenerated gas streams is desirable with the low cokeproducing crystalline zeolite catalyst so that an initial catalyst mixtemperature of at least 1175° F. in the dense fluid bed of catalyst willbe more easily attained.

In the arrangement of the present invention it is contemplatedsupplementing residual carbonaceous material such as coke transferred tothe regeneration system by the introduction of torch oil. In aparticular aspect it is contemplated adding torch oil to the spentcatalyst passed to the riser mixing zone or the torch oil may be addedwith the air passed to the riser mixing zone. It also is contemplatedadding the torch oil to an air line burner exit to aid with vaporizationof the torch oil. On the other hand, a second torch oil vaporizer may beseparately employed for injecting torch oil at spaced apart intervalsacross a lower portion of the dense fluid bed of catalyst to beregenerated. It is preferred in the combination operation of thisinvention to inject the torch oil to the riser mixing zone along withregeneration air as more specifically shown in the drawing.

The regenerating technique of the present invention relies upon aparticular relationship of operating parameters which will accomplishthe removal of carbonaceous deposits down to at least 0.05 weightpercent and preferably as low as about 0.03 weight percent or lower incombination with limiting the amount of carbon monoxide in thecombustion flue gases not to exceed about 0.15 mole percent. Thus it isessential to the processing concepts of this invention to rapidlyinitiate burning of deposited carbonaceous material at an elevatedtemperature of at least about 1175° F. with an amount of oxygencontaining regenerating gas such as air providing a catalyst temperaturerise of at least about 100 degrees and preferably sufficient to heat thecatalyst particles carried through the regeneration system to anelevated temperature of at least 1300° F. Furthermore, to reap theadvantage of the heat generated in the system, the regeneration gas flowrate is selected to provide a density or concentration of catalystparticles in the enlarged bottom portion of the regeneration zone withinthe range of 10 to 40 lbs/cu.ft. and in the upper most dispersedcatalyst phase section thereof at a catalyst particle concentrationbelow 8 lbs/cu.ft. and preferably below 2 lbs/cu.ft.

The contact time-temperature span relationship of the present inventionrequired to burn combustible materials is spread over the sequence ofcatalyst phases in the regeneration operation in a manner taking fulladvantage of each operating phase to achieve the burning of combustiblesand more efficient recovery of available heat generated in the catalystphases. Furthermore, the operating controls and arrangement of apparatusis selected to provide the desired mixing of spent catalyst with hotregenerated catalyst in an amount to more particularly optimize theregeneration operation. In this operating environment it is important tomaintain a proper pressure balance between vessels to achieve desiredcatalyst flow. That is, the pressure in the reactor side of theapparatus of the figure may be maintained relatively high to achievetransfer of catalyst from the stripper to the inlet of the riser mixer.On the other hand, the stripper adjacent the riser reactor may be at ahigher elevation in order to develop a necessary pressure head fortransferring catalyst as desired from the stripper to the riser mixer.Of course, a combination of reactor pressure and vessel height may beemployed to achieve the results desired.

In yet another embodiment, for ease of fabrication, the bulb portion ofthe riser regenerator may comprise upper and lower conical sectionsseparated by a cylindrical section of a diameter sufficient to maintaina dense fluid catalyst bed phase therein. In still another embodiment itis contemplated employing a relatively uniformly diverging upper sectionextending above said cylindrical section for restricting the upwardlyflowing dispersed catalyst phase herein described.

It will be recognized from the above discussion that a relativelydelicate balance in operating parameters is maintained to obtain adesired coke burning and removal thereof without producing undesiredoxygen and carbon monoxide concentrations in the combustion flue gasesand these operating restrictions are dictated in substantial measure bythe ratio of hot regenerated catalyst that can be mixed with spentcatalyst obtained from hydrocarbon conversion. For example, it has beenobserved that low initial catalyst mix ratios of regenerated catalyst tospent catalyst are accompanied by high concentrations of carbon monoxideand oxygen being emitted from the regenerator riser to the outletcyclones. However, as the carbon on spent catalyst is increased by achange in feed reaction conditions etc. or by the addition of torch oil,for example, in the regeneration system, the mix ratio of regeneratedcatalyst to spent catalyst must be adjusted as required to provide thedesired temperature profile in the regenerator.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE presents diagrammatically in elevation one arrangement ofapparatus for accomplishing the catalytic conversion of hydrocarbons andthe regeneration of catalyst particles in an upflowing catalystregeneration system wherein an upflowing relatively dense fluid mass ofcatalyst charged with a high temperature catalyst mixture is transformedinto a higher temeprature more dispersed catalyst phase regenerationoperation before separation of flue gases of restricted low CO contentfrom regenerated catalyst particles is accomplished.

DISCUSSION OF SPECIFIC EMBODIMENT

Referring now to the drawing, a hydrocarbon feed such as a gas oilboiling range feed is introduced by conduit 2 to the bottom of a riserconversion zone 4. Hot regenerated catalyst in conduit 5 provided withflow control valve 8 enters the bottom portion of riser 4 for admixturewith the oil feed to form a catalyst-oil suspension at an elevatedconversion temperature of at least about 850° F. and more usually atleast 1000° F. Additional gasiform reactant material comprising C₅ andlighter hydrocarbons, alcohols, ethers and combinations thereof may alsobe introduced with the gas oil feed. The suspension of hot catalyst ofregeneration in hydrocarbon material thus formed is passed upwardlythrough the riser conversion zone under high temperature hydrocarbonconversion conditions of at least 980° F. promoting the cracking of thegas oil feed to lower and higher boiling products including carbonaceousmaterial deposited on the catalyst. The products include gasoline, fueloils and normally gaseous hydrocarbon products. The hydrocarbon feedwith suspended catalyst particles may be maintained in the riserconversion zone for a hydrocarbon residence time within the range of 1to 10 seconds. However, a hydrocarbon residence time within the range of0.5 to 4 seconds may be employed with particular advantage when usinghydrocarbon conversion temperatures above 1000° F. and up to about 1100°F. Spaced apart hydrocarbon feed inlets 2' and 2" are provided in riser4 for the introduction of hydrocarbon feed material of the same, higheror lower boiling range. The suspension passed upwardly through riser 4is discharged from the upper end of the riser conversion zone into twoor more cyclonic separating means 14 and 14' as shown. Stripping gas andstripped hydrocarbons pass through cyclonic separating means 16. Ofcourse cyclone separators 14 and 16 may each be a plurality of cyclonicseparation means suitably connected to accomplish the results desiredwith respect to controlling the residence time the hydrocarbon contactsthe catalyst. Gasiform hydrocarbon material and stripping gas obtainedas provided below is withdrawn by conduits 18 and 20 communicating withplenum chamber 22 and withdrawal conduit 24. Conduit 24 communicateswith product separation equipment not shown. Catalyst particlesseparated by a velocity reduction in the enlarged vessel arrangement andby cyclonic means are collected as a bed of catalyst 26 which movesdownwardly through an annular stripping vessel about a substantialportion of the riser reactor and countercurrent to rising stripping gassuch as steam or other suitable inert stripping gas introduced byconduit 28. The stripping gas maintains the bed of catalyst 26 in adense fluid condition as it moves generally downward. The stripping gasremoves entrained hydrocarbon vapors and other strippable material fromthe catalyst as the catalyst moves downwardly through the strippingzone. Stripped catalyst is withdrawn by standpipe 30 provided with flowcontrol valve 32 and is passed to the bottom portion of a risermixing-catalyst regeneration zone 34. Riser mixer 34 herein describeddischarges into the lower portion of a dense fluid bed or mass ofcatalyst to be regenerated as herein provided. Regenerated catalystobtained as hereinafter defined, withdrawn by standpipe 36 and providedwith flow control valve 38 communicates with the lower portion of riser34 and provides hot regenerated catalyst at a temperature of at least1300° F. for mixing with the spent catalyst at a lower temperature inthe range of about 850° F. up to about 1000° F. to form a catalystmixture of at least 1175° F. This mixture is conveyed with air or oxygensupplemented regeneration gas through riser mixer 34 for discharge intothe lower portion of a dense fluid bed of catalyst 35 in the bulbportion of the regeneration zone.

In an enlarged settling section comprising the upper portion of theregenerator vessel about the upper discharge end of riser 46 a densefluid bed of regenerated catalyst comprising the hot freshly regeneratedcatalyst particles recovered from the dispersed phase regenerationsection is maintained in a dense fluid bed condition by a hot fluidizinggas such as a hot CO₂ rich product gas, an oxygen containing gas orother suitable gases added by conduits 39 and 41.

In the bottom enlarged bulb portion of the catalyst regenerator, arelatively large dense fluid bed or mass of catalyst particles ismaintained under catalyst regenerating temperature conditions generallyabout 1200° F. and a concentration of catalyst particles in the catalystphases within the range of 10 to 40 lb/cu.ft. and more usually at least30 lbs/cu.ft. A first regeneration gas stream 44 comprising air oroxygen enriched gaseous material is introduced to the bottom portion ofriser 34 for admixture with the catalyst streams in conduits 30 and 36introduced thereto. Heating of the regeneration gas or air streamintroduced by conduits 40, 42 and 44 in equipment not shown ispreferred. Thus with a spent catalyst temperature of about 960° F. andcontaining 0.9 wt.% carbon thereon, it is desirable to preheat theregeneration gas to about 325° F. and mix a 1 to 1 ratio of spentcatalyst in conduit 30 to recycle regenerated catalyst in conduit 36 ata temperature of at least about 1350° F. In the dense fluid bed ofcatalyst, the temperature of the bed is caused to be elevated by theburning of carbonaceous material with introduced oxygen containingregeneration gas. Furthermore, combustion of carbonaceous material israpidly initiated by the hot catalyst mix distributed into the lowerdense bed of catalyst with oxygen containing combustion gases by theoutlet of mixing zone 34. Transporting the catalyst overhead from thedense catalyst through the dispersed catalyst phase regeneration sectioncompletes the removal of carbonaceous deposits within the processinglimits selected and desired, transform carbon monoxide to carbon dioxideand produces a less dense catalyst-combustion gas suspension temperatureof at least 1350° F. and preferably at least about 1375° F. As mentionedabove, the concentration of catalyst particles in the upwardly flowingsuspension is generally decreased in the direction of flow although itnot necessarily need be depending on gas velocity conditions employed toproduce catalyst particle concentrations in suspending flue gases below5 lbs/cu.ft. before discharge from the riser regenerator into anenlarged catalyst separation zone. In any event the dispersed suspendedcatalyst phase passing into the enlarged settling zone is preferablyless than 3 lbs/cu.ft. whether or not cyclonic separators are employed.Higher concentrations of catalyst particles can be employed withcyclonic separating means.

The catalyst combustion gas suspension is discharged in a specificarrangement from the upper end of riser regenerator 46 through aplurality of outwardly extending arm means open on the bottom side orprovided with downwardly facing openings promoting the separation ofcatalyst particles from flue gases.

Additional oxygen containing gas such as air may be added to theupflowing suspension in riser 46 by one or more spaced inletsrepresented by conduit 48. The catalyst-combustion gas suspension passedupwardly through the restricted cross-sectional regeneration zone orriser 46 discharges against the upper closed end 50 which deflects thesuspension outwardly through the plurality of elongated peripheral slotsor arm means with openings facing downwardly into the enlarged settlingsection 53 of vessel 52. Discharging the suspension into the enlargedzone 53 lowers the velocity of the suspension thereby causing thecatalyst particles to settle out and separate from flue gases. Insettling zone 53 a major portion of the catalyst particles separate fromthe combustion flue gases before the flue gases pass through a pluralityof cyclone separators represented by separators 54 and 56. Combustionflue gases comprising carbon dioxide rich gases are removed fromseparators 54 and 56 by conduits 58 and 60, plenum chamber 62 andwithdrawal conduit 64.

Catalyst particles separated at an elevated regeneration temperature upto as high as 1600° F. as above identified are collected as an annulardense fluid bed of catalyst 66 about an upper portion of regeneratorriser 46. The regenerated catalyst thus collected is withdrawn bystandpipes 5 and 36 for use as herein discussed without significantcooling thereof. The catalyst in conduit 5 may be stripped in anexternal stripper not shown, if desired.

The catalyst regeneration method and system of the present invention isunique over that of the known prior art by at least the riser mixing ofhot freshly regenerated catalyst with coke contaminated catalystseparated from the conversion zone in an amount sufficient to provide anelevated mix temperature of at least 1175° F. This high temperature mixof catalyst is sufficient for promoting the combustion of carbonaceousdeposits in the presence of added oxygen containing regeneration gassuch as air in an initial riser contact zone and the conversion offormed carbon monoxide to carbon dioxide is particularly promoted on aonce through basis in the upflowing suspended catalyst atmospherethereabove varying in particle concentration or density from about 40lb/cu.ft. down to about 3 lbs/cu.ft. and less.

Having thus generally described the invention and discussed specificembodiments in support thereof, it is to be understood that no unduerestrictions are to be imposed by reasons thereof.

I claim:
 1. Apparatus for effecting the regeneration of fluid catalystparticles which comprises,a first riser means of larger diameter in thelower bottom portion thereof than the portion thereabove, a second risermeans terminating in the said lower bottom portion of said first risermeans, said second riser means being capped at its upper end andprovided with a plurality of vertical elongated adjacent slots in theupper periphery thereof, said first riser means extending upwardly intoand discharging into an enlarged catalyst collecting chamber, open endedfirst conduit means provided with valve means extending from a bottomportion of said catalyst collecting chamber to a bottom portion of saidsecond riser means, second conduit means connected to the bottom portionof said second riser means for transfer of coke contaminated catalystparticles thereto, third conduit means for withdrawing regeneratedcatalyst from a bottom portion of said catalyst collecting chamber, andcyclonic separating means positioned in an upper portion of saidcatalyst collecting chamber in open communication with means forwithdrawing gasiform material from an upper portion of said catalystcollecting chamber.
 2. The apparatus of claim 1 wherein a plurality ofarms extend radially from the upper discharge end of said first risermeans and each arm discharges a suspension of catalyst and gaseousmaterial generally downward in said catalyst collecting chamber. 3.Apparatus for effecting the regeneration of fluid catalyst particleswhich comprises,a first riser means of larger diameter in the lowerbottom portion thereof than the portion thereabove, a second riser meansterminating in the said lower bottom portion of said first riser means,said second riser means being capped at its upper end and provided withradial discharge means at the upper periphery thereof arranged todischarge laterally into the bottom portion of said first riser means,said first riser means extending upwardly into and discharging into anenlarged catalyst collecting chamber, open ended first conduit meansprovided with valve means extending from a bottom portion of saidcatalyst collecting chamber to a bottom portion of said second risermeans, second conduit means connected to the bottom portion of saidsecond riser means for transfer of coke contaminated catalyst particlesthereto, third conduit means for withdrawing regenerated catalyst from abottom portion of said catalyst collecting chamber, and cyclonicseparating means positioned in an upper portion of said catalystcollecting chamber in open communication with means for withdrawinggasiform material from an upper portion of said catalyst collectingchamber.
 4. The apparatus of claim 3 wherein a plurality of arms extendradially from the upper discharge end of said first riser means and eacharm discharges a suspension of catalyst and gaseous material generallydownward in said catalyst collecting chamber.